Basic oxygen steel making facility and method of oxygen refining of steel

ABSTRACT

A basic oxygen steel making facility and method of oxygen refining of steel is disclosed wherein there are two or more mobile furnaces, each comprising a wheeled support on which is fixed an upright top blow converter that moves around a quadrangle about which are arranged charging, blowing, and teeming stations, with provision being also made for removing slag after each cycle of operation. Two opposed sides of the quadrangle have tracks at an upper level on which the mobile furnaces move in succession on their own wheels, while the other two opposed sides have tracks at a lower level. On each of these two lower level tracks is a transfer truck or bridge that may shuttle back and forth between the ends of the upper level tracks. Each of these transfer bridges has a deck with tracks thereon that is brought by movement of the bridge into vertical and horizontal register with the ends of the upper level tracks, and which, then, in effect, forms extension thereof, so that the mobile furnaces may roll from one of the upper level tracks onto the bridge and be carried by the bridge to the other of the upper level tracks, and then roll from the bridge on its own wheels onto other upper level tracks. This arrangement makes possible an operation in which each of the two or furnaces are charged in succession, blown with oxygen in succession, and thereafter tapped and recycled, so that one conventional blowing station can serve each of the furnaces while the pre-blowing and post-blowing operations are carried out elsewhere. Provision is made off one corner of the quadrangle for relining a furnace and holding another one in reserve.

United States Patent 1 1 Freeberg et al.

1451 July 17, 1973 BASIC OXYGEN STEEL MAKING FACILITY AND METHOD OF OXYGEN REFINING OF STEEL [76] Inventors: Charles A. Freeberg, 343 Newbum Drive, Pittsburgh. Pa. 15216; Alfred G. Ganss, deceased, late of New Kensington, Pa.; Shirley Ganss, legal representative, 435 Argon Drive, Lower Burrell, Pa. 15068 [22] Filed: Dec. 1, 1970 [21] Appl. No.: 94,101

Primary Exizminer-Gerald A. Dost Attorney-Partnelee, Utzler & Welsh [5 7] ABSTRACT A basic oxygen steel making facility and method of oxygen refining of steel is disclosed wherein there are two or more mobile furnaces, each comprising a wheeled support on which is fixed an upright top blow converter that moves around a quadrangle about which are arranged charging, blowing, and teeming stations, with provision being also made for removing slag after each cycle of operation. Two opposed sides of the quadrangle have tracks at an upper level on which the mobile furnaces move in succession on their own wheels, while the other two opposed sides have tracks at a lower level. On each of these two lower level tracks is a transfer truck or bridge that may shuttle back and forth be tween the ends of the upper level tracks. Each of these transfer bridges has a deck with tracks thereon that is brought by movement of the bridge into vertical and horizontal register with the ends of the upper level tracks, and which, then, in effect, forms extension thereof, so that the mobile furnaces may roll from one of the upper level tracks onto the bridge and be carried by the bridge to the other of the upper level tracks, and then roll from the bridge on its own wheels onto other upper level tracks. This arrangement makes possible an operation in which each of the two or furnaces are charged in succession, blown with oxygen in succession, and thereafter tapped and recycled, so that one conventional blowing station can serve each of the furnaces while the pre-blowing and post-blowing operations are carried out elsewhere. Provision is made off one corner of the quadrangle for relining a furnace and holding another one in reserve.

8 Claims, 8 Drawing Figures PATENIED Jill 7 sum 2 or 7 INVENTORS CHARLES A. FREEBERG,

ALFRED 6. GAIVSS Meir Attorneys PATENTED JUL 1 7 SHEU 3 [IF 7 INVENTORS I" t: CHARLES 4. mites/m, E ALFRED a. amvss Hie/ Attorneys Plumnaum 3.146.325

shit! u UF 7 nwew TORS- CHARLES A. FREEEER'G, ALFRED 0. 64/0/55 Illa/r Attorneys PAIENIEU 1 3. 746.325

sum 5 or 7 mvE/v TORS can/n ES 4. FREEBERG, ALFRED a. amvss By W41,

their A Ilornays PATENIEB JUL 7 97 SHEEI 7 [IF I s R 0 T N E V N CHARL ES 4. FREEBE'RG, ALFRED 0. 64/1/88 By M W o ajbw,

Mair Attorneys BASIC OXYGEN STEEL MAKING FACILITY AND METHOD OF OXYGEN REFINING OF STEEL This invention relates to a basic oxygen steel making facility and to a method of oxygen refining of steel, and more particularly to an installation and method which uses movable oxygen furnaces.

In the conventional oxygen steelmaking shop the furnaces used are installed in a fixed position. Usually, two furnaces are used. Each of the furnaces requires its own complete blowing station which includes a lance crane, oxygen lance, teeming ladle transfer car, slag pot transfer car, flux additive system, control pulpit, ladle additive system, combustion chamber or quencher, and an isolation valve from the gas cleaning system. The shop production is normally calculated on the basis of one of the furnaces being in operation while the other is on standby. Concurrent blowing of both furnaces is possible if the shop has adequate oxygen generating facilities and if the gas cleaning system is suitably sized to handle the gas volume from the two blown furnaces. Alternate blowing, however, is the most practical approach with the full recognition that in a thirty day period about eight days are lost on each furnace for refractory lining replacement. In addition, one furnace hood, lance crane, transfer car and additive system is always nonproductive.

The installation of this invention uses movable furnaces and a single blowing station consisting of a hood, lance crane, flux and alloy additive system, gas cleaning system, control pulpit, ladle additive system, and oxygen generating station. Also, there is no need for transfer cars, as in the conventional system, since the furnaces can be transported on their own carriage to a teeming station and to a slag pit. More importantly, however, is the fact that productivity can be increased considerably by this invention. With this invention the non-productive steps viz. charging of metal, tapping of the steel and slag-off associated with steelmaking are not performed at the blowing station, but are performed elsewhere while another furnace is at the blowing station. In the conventional shops the nonproductive steps must necessarily be carried out at the blowing station. The time required for the various operations comprising one heat of a conventional system is as follows:

Charge Scrap minutes Charge Hot Metal 2 minutes Char e Fluxes and Alloys minutes and low Oxygen Analysis and Reblow 5 minutes Tap Steel 5 minutu Slag-Off 5 minutes Total 42 minutes In comparison to the above, the time required at the blowing station of this inventionis anticipated to be as follows:

Move Furnace into Station 2 minutes Charge Fluxes and Alloys 20 minutes and low Oxygen Analysis and Reblow 5 minutes Move Furnace from Station 2 minutes Total 29 minutes Thus, two heats per hour using two furnaces could be processed through a single blowing station by this invention and given an annual productive capacity comparable to a conventional installation using three furnaces each of which requires its own blowing station.

More particularly, we provide a basic oxygen steel making facility which preferably comprises: two parallel trackways at one level; two other parallel trackways on a lower level at right angles to and at the ends of the first two trackways, the several trackways defining a quadrangle; a first transfer bridge on one of the'second trackways movable back and forth between the end of one of the first trackways and the corresponding end of the other, the transfer bridge having tracks thereon which register horizontally and vertically with, and in effect form extensions of the end of the first trackways with which the bridge registers; a second similar movable transfer bridge on the other of the second trackways with tracksthereon which register horizontally and vertically with and form in effect an'extension of the end of the first trackways to which it is moved and with which it registers; at least two carriage-supported upright top-blow basic oxygen converter furnaces, the carriage of which are arranged to roll on the first trackways and the extension-providing tracks on the first and second bridges; and furnace charging, blowing, and teeming stations arranged around the quadrangle to which each carriage-supported furnace is moved in succession, the blowing station having a gas offtake hood beneath which the furnaces are centered. Preferably, the charging, blowing, and teeming stations are aligned with each other on one trackway, termed the furnace blowing aisle. The trackway parallel to the furnace blowing aisle is termed the furnace return aisle. In addition, there is also provided a hot metal processing station, a furnace reline station, a slag pit, and a scrap aisle. The slag pit is preferably arranged at the end of the furnace return aisle so that a furnace may be moved up to it for slag-off. The reline station is preferably off to the side of the furnace return aisle and is arranged so that a transfer bridge may transport a furnace to that station for refractory relining.

The method of this invention relates to the oxygen refining of steel utilizing conventionally shaped and completely independent top blow movable furnace assemblies passed and processed independently of one another through the various stations of a basic oxygen installation, including a charging station, blowing station, and teeming station, which method comprises preferably, the steps of: positioning a first movable furnace assembly at the charging station; charging the first furnace assembly with metal; moving the charged first furnace assembly to the blowing station in a furance blowing aisle without lifting the furnace above ground level; converting the metal in'the first furnace assembly and removing the gases directly to a gas cleaner and scrubber; positioning a second furnace assembly means at the charging station and charging it with metal, which charging may be done while the metal in the first furnace assembly is being converted; moving the-first furnace assembly to the teeming station and tapping off the molten steel; transferring the first furnace assembly to a furnace return aisle without lifting the assembly above ground level by moving the furnace assembly at least part way transversely to the furnace blowing aisle;

.and repeating the moving, converting, transferring, tapping, and transporting steps on the second furnace assembly. Additional steps to the method of this invention are also provided, such as, moving one of the furnace assemblies to a refractory reline station prior to positioning it at the charging station, and charging the furnace with scrap metal and preheating it prior to moving the furnace assembly to the blowing station.

Other details and advantages of this invention will become apparent as the following description of a present preferred embodiment thereof and a present preferred method of practicing the same proceeds.

In the accompanying drawings we have shown a present preferred embodiment of this invention and have illustrated a present preferred method of the same in which:

FIG. 1 is a perspective view, partially in schematic, of a basic oxygen steel making facility embodying the present invention, with parts of the building and other structure cut away to show details of construction;

FIG. 2 is a floor plan view mostly in schematic, of the basic oxygen furnace installation shown in FIG. 1;

FIG. 3 is a view taken along the line 3-3 of FIG. 2 showing details of construction of, among other things, the furnace blowing aisle;

FIG. 4 is a view taken along the line 44 of FIG. 2 showing details of construction of, among other things, the transfer aisles;

FIG. 5 is a view taken along the line 5-5 of FIG. 2 showing details of construction of, among other things, the furnace reline station in its relationship to a transfer aisle;

FIG. 6 is a view taken along the line 6-6 of FIG. 2 showing details of construction of, among other things, the hot metal processing station and the scrap metal aisle;

FIG. 7 is a side elevation view of the movable furnace arranged on a travelling bridge as illustrated in the above figures, showing more details of construction; and

FIG. 8 is a front elevation view of the furnace and travelling bridge of FIG. 7.

Referring now to the drawings, and particularly, to FIGS. 1 and 2, there is shown a basic oxygen steel making facility generally designated by the numeral 10, including a suitable building structure 12 for housing the installation. The basic areas comprising the facility are the furnace blowing aisle 14 which includes a hot metal and scrap metal charging station 16, preheat station 18, blowing station 20, and teeming station 22; first transfer aisle 24; furnace return aisle 26; slag pit 28; second transfer aisle 30; hot metal processing station 32; furnace reline station 34; scrap aisle 36; gas scrubbing system 38; and movable basic oxygen furnace assemblies 40. The furnace blowing aisle l4, first transfer aisle 24, furnace return aisle 26, and second transfer aisle 30 are arranged in a quadrangle with the blowing and return aisles at ground level being intersected by the opposite transfer aisles on a plane below the blowing and return aisles. This quadrangle arrangement will be more fully understood as this description proceeds.

The furnace blowing aisle 14 as shown in FIGS. 1, 2, and 3 extends from adjacent the scrap aisle 36, and transversely thereto, to the teeming station 22. The furnace blowing aisle 14 is formed from suitable construc tion material, such as reinforced concrete for supporting the weight of the furnace assemblies 40. The length of the blowing aisle 14 between the charging station 16 and first transfer aisle 24 is at ground level, and has thereon a trackway made up of transversely spaced support rails or tracks 42 anchored to the concrete bed and upon which the wheels of the carriage of the furnace assemblies 40 ride, as will be described hereinafter,'and hot (i.e. current conducting) rails or tracks 44 place within the spacing of the support tracks 42 and connected with a source of electrical power, not shown, for engaging power contact wheels on the carriages of the furnace assemblies 40 for operating the drive motors and tilting motors of the furnace assemblies. The tracks 42 and 44 are interrupted by the first transfer aisle 24 between the blowing station 20 and the teeming station 22. The first transfer aisle 24 lies in plane below the plane of the central portion of the furnace aisle including the preheat and blowing stations, and for clarity of description the area of intersection will be considered as part of the furnace blowing aisle 14. Thefirst transfer aisle 24 extends laterally from the furnace blowing aisle 14 to intersect the furnace return aisle 26. Longitudinally extending pairs of spaced support tracks 48 are anchored on the ground surface of the first transfer aisle 24 and current conducting hot tracks 50 are anchored inbetween the support tracks. The bed of the first transfer aisle 24 is formed from construction material, such as reinforced concrete, of suitable strength for supporting the movable furnace assembly 40.

Each of the movable furnace assemblies 40, as shown in FIGS. 7 and 8, includes an open topped, generally cylindrically shaped top-blow basic oxygen steel making converter or furnace 52 suitably shaped with regard to height to diameter relationship and volume, and a carriage 54 for supporting the furnace 52. The carriage 54 includes a trunnion ring member 56 suitably sized to surround the furnace 52 at an intermediate portion thereof, with the trunnion ring member and furnace shell being provided with bracket means, not shown, for securing the furnace thereto. The carriage 54 is pivotally arranged, as by trunnion mounts 58, on the tops of oppositely positioned elongated pedestals 60 and 62. Each of the pedestals 60 and 62 supports a rail engaging wheel assembly 64 at the opposite portions of the bottom surface thereof. Each of the wheel assemblies 64 includes two tandem outboard rail engaging wheels 66 shaped to engage the support tracks 42 running along the furnace blowing aisle l4, and inboard wheels 68 shaped to engage the hot tracks 44 also on the furnace blowing aisle 14. The inboard wheels 68 will conduct the electrical current from the hot tracks 44 through suitable wiring to drive motors located within either pedestal 60 or 62 which motors will drive all the wheels 66 or 68 through power transmissions to thereby propel the carriage 54 along the tracks 42 and 44. The inboard wheels 68 also conduct power to tilting motors, arranged within either pedestal 60 or 62 and coupled to the journals of the trunnion mounts 58, for rotating the fumace' 52. The drive and tilting motors are not illustrated in the drawings since they per se do not form part of this invention and, additionally, it would be readily apparent to one skilled in the art as to how to arrange the motors to perform their respective functions. The carriage 54' is shown in FIGS. 7 and 8 as resting on the top of a transfer or travelling bridge 70 which includes a flat, generally square shaped platform 72 supporting a rail engaging wheel assembly 74 at each corner portion of the bottom surface thereof. The wheel assemblies 74 include tandem outboard wheels 76 shaped for engaging tracks 48 in the first transfer aisle 24 and tandem inboard wheels 78 shaped to engage the hot tracks 50 also in the first transfer aisle. The inboard wheels 78 will conduct electrical power from the hot tracks 50 to drive motors, not shown, located within the confines of platform 72 for motivating the wheels 76 and 78 to thereby propel the travelling bridge 70 along the first transfer aisle 24. A pair of spaced support tracks 80 is fixed to the top surface of the platform 72. The support tracks 80 are arranged to align with tracks 42 when the travelling bridge 70 is positioned between the blowing station and teeming station 22. Similarly, a pair of hot tracks 82 is arranged within the spacing of the support rails 80 for alignment with the hot tracks 44. Thus, the carriage 54 of a furnace assembly 40 may be propelled onto the platform 72 and across onto the tracks 42 and 44 at the teeming station 22, or stopped on the platform 72 and the travelling bridge 70 propelled along the first transfer aisle 24 to the furnace return aisle 26.

The furnace return aisle 26 is laterally along side and generally parallel with the furnace blowing aisle 14, and extends from the teeming station 22 to the slag pit 28. The furnace return aisle 26 is intersected by the second transfer aisle which runs from the charging station 16 to the hot metal processing station 32. The section of the return aisle 26 between the first and second transfer aisles 24 and 30, respectively, is at ground level and on the same level as the central portion of the furnace blowing aisle 14 including the preheat and blowing stations 18 and 20, respectively. Likewise, the section of the return aisle around the slag pit 28 is at ground level. The second transfer aisle 30 is below the planes of the ground level section of the furnace return and furnace blowing aisles and is at the same recessed level as the first transfer aisle 24. A pair of transversely spaced support tracks 86 corresponding in configuration and spacing to the support tracks 42 of furnace aisle 14 and support tracks 80 on the platform 72 of travelling bridge 70, is anchored to the ground level sections of the furnace return aisle 26. Similarly, a pair of transversely spaced hot tracks 88 corresponding in configuration and spacing to the hot tracks 44 of furnace aisle 14 and hot tracks 82 on the platform 72 of travelling bridge 70, is anchored within the spacing of tracks 86 on the ground level sections of the furnace return aisle 26. Thus, the furnace assembly may be driven onto the tracks 86 and 88 of furnace return aisle 26. The ground level sections of the furnace return aisle 26 are constructed of strong construction material, such as reinforced concrete, for providing proper support to the furnace assemblies 40.

As mentioned previously, the second transfer aisle 30 extends from the hot metal processing station 32 to intersect the furnace blowing aisle 14. The intersection of the transfer aisle 30 and the blowing aisle 14 defines the charging station 16 and for sake of clarity of description the intersected area-charging station--will be considered as part of the blowing aisle 14. The cross-sectional shape of the second transfer aisle 30 is identical to the first transfer aisle 24. included in the second transfer aisle 30 are pairs of transversely spaced support tracks 90 and hot tracks 92 within the spacing of the support tracks, such tracks being identical in configuration and spacing to the support and hot tracks 48 and 40, respectively, of first transfer aisle 24. Thus, a travelling bridge 70, as described with regard to first transfer aisle 24, is transportable over the tracks Mind 92. when a travelling bridge 70 in the second return aisle 30 is positioned between the ground level sections of the furnace return aisle 26 a bridge is formed between the interupted tracks 86 and 88, to thereby permit the furnace assembly 40 to travel between the slag pit 28 and central portion of the return aisle 26. Similarly, when a travelling bridge is positioned at the charging station 16 a furnace assembly 40 may be passed between the charging station and the preheat and blowing stations 18 and 20, respectively.

The hot metal processing station 32 and furnace reline station 34 are arranged on ground level on opposite sides of the left end portion of the second transfer aisle 30, as viewed in FIG. 2. The hot metal processing station 32 contains the usual equipment associated with such a station as used in conventional installations, such as track for supporting hot metal torpedo cars 102, and a charging ladle 104 positioned in a pit 106 for receiving hot metal from the torpedo cars 102. An overhead crane 108 runs on rails extending from the ladle pit 106 to the charge station 16 and is used for carrying ladles 104 therebetween.

The furnace reline station 34 includes two identical reline ports 108 and 110 arranged side by side, each including pairs of transversely spaced support tracks 112 and hot tracks 114 within the spacing of the support tracks, with such tracks being identical in configuration and spacing to the support and hot tracks 80 and 82 on the travelling bridges 70. Thus, when a travelling bridge 70 in the second transfer aisle 30 is aligned with either reline port 108 or 110 the respective tracks thereof are aligned so that a furnace assembly 40 may be propelled into the port. A deck 115 is supported above the reline ports 108 and 110, and includes openings 116 and 118 therethrough arranged so that the open top of the furnaces 52 align therewith, to permit refractory block to be lowered into the confines of the furnace. A block storage area 120 is located alongside the reline ports 108 and 110. An overhead crane 122 is supported on rails above the storage area 120 and deck 115 for block handling and service of the furnace reline station 34 in general.

The scrap aisle 36 is located to the right of the charging station 16 as viewed in FIG. 2 and includes a series of parallel tracks 124 for supporting railroad cars 126 carrying scrap into the station. Scrap is loaded from the railroad cars into scrap charging buckets 128 situated on top of a railroad flat car 130 which may be driven to the left end of the tracks when the buckets 128 may then be picked up by the charging crane 108. An overhead crane 132 is arranged on rails for servicing the scrap aisle 36.

In operation, a travelling bridge 70 with a furnace assembly 40 thereon is positioned at the charging station 16. The crane 108 picks up a ladle 104 of hot metal from the ladle pit 106 and carries it to the charging station for charging into the furnace. The charged. furnace assembly 40 may then be moved to the blowing station 20. Alternatively, the furnace assembly 40 at the charging station 16 may be charged with scrap metal, in which case the furnace assembly would be moved to the scrap preheat station 18, heated and returned to the travelling bridge 70 and charged with hot metal and then moved to the blowing station 20. Alloying elements may be added to the furnace assembly 40 before and after blowing, by discharging the alloys from the storage and distribution system generally designated 130 and located above the preheat and blowing stations 18 and 20 as shown in FIGS. 1 and 4. The blowing station 20 includes all of the auxiliary equipment necessary for oxygen refining of steel. For example, there is included the gas cleaning system 38 having ducting 1410 arranged to mate at one end to the opening of a furnace 52, whereby the top gases pass from the furnace upwardly through a quencher 142, a scupper 144, a scrubber 146, dust eliminator 148, and finally through motor driven exhaust fans 150 and out of a stack 152. Also, there is provided oxygen lances 154, a crane 156 for moving the lances from storage into the furnace 52 and a lance guide 158. An operator in a conrol room 160 controls all of the operations in refining of the steel.

After the steel is refined, the travelling bridge 70 in first transfer aisle 24 is positioned in alignment with the furnace blowing aisle l4 and the furnace assembly 40 propelled onto the bridge and then into the teeming station 22 where it is tilted to pour molten refined steel into a teeming ladle 164 located in a tapping pit 166. The ladle 164 is then lifted out of the pit 166 by an overhead crane 168 and poured into molds 170 arranged on flat cars on teeming track 172. Additives may be added to the teeming ladle 164, and suitable equipment, not shown, such as additive storage bins, and weigh hoppers with vibrating feeders may be provided for that purpose.

After the furnace 52 is emptied of molten metal, the furnace assembly 40 is moved back onto the travelling bridge 70 which is then moved laterally into alignment with the furnace return aisle 26. The furnace assembly 40 is driven along the furnace reline aisle 26 to a travelling bridge 70 in the second transfer aisle 30, across the bridge and into the area of the slag pit 28 where the slag is poured out of the furnace 52. The furnace assembly- 40 is then returned to the travelling bridge 70 which is then either moved to the charging station 16 for beginning another refining cycle or to the furnace reline station 34 where the furnace assembly 40 may be moved into one of the reline ports 108 or 110 where relining of the furnace 52 may commence.

While a furnace assembly 40 is at the blowing station 20, another furnace assembly may be at the charging station 16 being charged with metal. After the first furnace assembly 40 is driven away from the blowing station 20 to the teeming station 22 the second furnace assembly may be moved into position in the blowing station. While two furnace assemblies 40 are being cycled through the blowing station, a third furnace assembly 40 could be in the furnace reline station 34 being relined.

Various other equipment and facilities may be provided as part of the above described installation. For example, a maintenance and repair shop, electrical power substation, wash rooms, laboratory, and office can be readily arranged within the confines of structure 12. Also, a ladle reline station, stopper rod oven, and

make up area can likewise be provided as those skilled in the art may readily recognize.

Thus, by virtue of this invention, we provide a novel basic oxygen steel making facility and method of refining steel. Our preferred form uses a basic quadrangular shaped flow path for multiple movable furnaces. We illustrated and described one form of the quadrangular arrangement contemplated within the scope of this invention. It should be apparent, however, that various other quadrangular arrangements are possible. For example, the charging station may be at ground level with blowing being conducted on the travelling bridge movable in a blowing aisle disposed below the charge aisle, tap-off could be conducted at a teeming station located in a teeming aisle at ground level, transfer of the furnace would be made on a travelling bridge in an aisle below the teeming and charging aisles, the slag pit could be off of the transfer aisle somewhere between the teeming and charging aisles, or the slag pit could be at the end of an aisle off of and below a teeming aisle; the charging station could be in a lower level aisle and the furnace transported on a transfer aisle at ground level to a travelling bridge in a lower level aisle where it will be positioned at a blowing station, and then tapoff being conducted at a teeming station located at ground level. The possibilities of the various arrangements of our preferred quadrangular facility, and method of steel making, are just too numerous to de scribe herein. However, regardless of what quadrangular pattern is selected within the scope of this invention, our facility and method makes possible an operation in which each of two or more furnaces are charged in succession, blown with oxygen in succession, and thereafter tapped and recycled, so that one conventional blowing station can serve each of the furnaces while the preblowing and post-blowing operations are carried out elswhere.

It is noted that our invention need not be confined to a quadrangular shape flow path so long as one leg of the flow path is at a lower level and transverse to two other generally parallel legs. For example, our blowing aisle could be at ground level followed by a winding track system'which would end up at a furnace return aisle generally parallel to the blowing aisle, and the furnace could be transferred to the blowing aisle on a travelling bridge disposed in an aisle below the level of and transverse to the blowing and return aisles. However, the quadrangular arrangement would be the most efficient and is preferred.

While we have shown and described a present preferred embodiment of this invention and have illustrated a certain present preferred method of practicing the same, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

We claim:

1. A multi-station metal refining facility comprising:

two parallel first trackways at one level;

two other parallel second trackways on a lower level at right angles to and at the ends of said first two trackways, the several trackways defining a quadrangle;

a first transfer bridge on one of said second trackways movable back and forth between the end of one of said first trackways and the corresponding end of the other, said transfer bridge having tracks thereon which register horizontally and vertically with, and in effect forms extensions of the end of the first trackways with which the bridge registers;

a second similar movable transfer bridge on the other of said second trackways with tracks thereon which register horizontally and vertically with and form in effect an extension of the end of the first trackways to which it is moved and with which it registers;

at least two carriage supported upright metal refining furnaces the carriages of which are arranged to roll on said first trackways and the extension-providing tracks on said first and second bridges;

furnace charging, blowing, and teeming stations arranged around said quadrangle to which each carriage-supported furnace is moved in succession, the blowing station having a gas offtake hood beneath which the furnaces are centered; and at least one of said lower level trackways has an extension beyond a corner of the quadrangle with at least two furnace relining stations therealong, each relining station having a transverse track at the level of said upper level trackways and with which the track on the movable bridge that travels along said extended lower level trackway may be brought into register, whereby a furnace requiring relining may be carried out of the quadrangle on said movable bridge and rolled onto one of said transverse tracks and a previously relined furnace on the other of said transverse tracks be immediately moved onto the bridge to replace the one so removed for relining, whereby the operating sequence may continue without interruption. 2. The apparatus specified in claim 1, wherein said facility comprises a basic oxygen steel refining facility. 3. A basic oxygen steel making facility as set forth in claim 2 including a hot metal processing station means disposed laterally to one side of said furnace blowing and furnace return aisles, and including hot metal processing cars, hot metal charge ladles, and transport means for carrying the ladles to and from the furnace.

4. A basic oxygen steel making facility as set forth in claim 2 of said first track means has an interrupted section between said blowing and teeming stations; and said first transfer aisle extends transversely across the interrupted first track means section to intersect said furnace return aisle.

5. A basic oxygen steel making facility as set forth in claim 2 including a scrap metal station disposed laterally of said furnace blowing and furnace return aisles on the side thereof opposite to the hot metal processing station, and including scrap transfer cars and charging buckets, and transport means for carrying the buckets to and from the furnace.

6. A basic oxygen steel making facility as set forth in claim 2 wherein said furnace return aisle extends beyond the charging station to a slag pit.

7. A basic oxygen steel making facility as set forth in claim 2 including a furnace reline station disposed laterally of, said furnace return aisle and on the side thereof opposite said furnace blowing aisle; and said second movable bridge is also arranged for transferring said furnace assembly between said furnace return aisle and said furnace reline station.

8. A basic oxygen steel making facility as set forth in claim 2 wherein said furnace blowing aisle includes a scrap metal preheat station arranged between the charging and blowing stations. 

2. The apparatus specified in claim 1, wherein said facility comprises a basic oxygen steel refining facility.
 3. A basic oxygen steel making facility as set forth in claim 2 including a hot metal processing station means disposed laterally to one side of said furnace blowing and furnace return aisles, and including hot metal processing cars, hot metal charge ladles, and transport means for carrying the ladles to and from the furnace.
 4. A basic oxygen steel making facility as set forth in claim 2 of said first track means has an interrupted section between said blowing and teeming stations; and said first transfer aisle extends transversely across the interrupted first track means section to intersect said furnace return aisle.
 5. A basic oxygen steel making facility as set forth in claim 2 including a scrap Metal station disposed laterally of said furnace blowing and furnace return aisles on the side thereof opposite to the hot metal processing station, and including scrap transfer cars and charging buckets, and transport means for carrying the buckets to and from the furnace.
 6. A basic oxygen steel making facility as set forth in claim 2 wherein said furnace return aisle extends beyond the charging station to a slag pit.
 7. A basic oxygen steel making facility as set forth in claim 2 including a furnace reline station disposed laterally of said furnace return aisle and on the side thereof opposite said furnace blowing aisle; and said second movable bridge is also arranged for transferring said furnace assembly between said furnace return aisle and said furnace reline station.
 8. A basic oxygen steel making facility as set forth in claim 2 wherein said furnace blowing aisle includes a scrap metal preheat station arranged between the charging and blowing stations. 